Question

I have two arraylist

ArrayList<String> a1
ArrayList<String> a2

I want to check if all the elements of a1 are present in a2.
this is what I was trying which I got from a question on SO

if (Arrays.asList(a2).containsAll(Arrays.asList(a1)))
{a2ContainsA1=true;}

which is not giving consistent results…is there any other way of doing this?

Answer 1

Not sure if I understand your question correctly, why are you using Arrays.asList() ?

Tried this:

    ArrayList<String> a1 = new ArrayList<String>();
    ArrayList<String> a2 = new ArrayList<String>();

    a1.add("a");
    a1.add("b");
    a2.add("b");
    a2.add("a");

    System.out.println(a2.containsAll(a1));

And it outputs true
Adding an additional element to a1 will fail it (as expected):

     ArrayList<String> a1 = new ArrayList<String>();
    ArrayList<String> a2 = new ArrayList<String>();

    a1.add("a");
    a1.add("b");
    a1.add("c");
    a2.add("b");
    a2.add("a");

    System.out.println(a2.containsAll(a1));

And it outputs false